DE102016104753B4 - Driving assistance system for a vehicle - Google Patents

Abstract

A travel support system for a vehicle which causes the vehicle to follow a target travel route through steering control and deceleration control, the travel support system comprising: a target steering angle calculating unit which, as a target steering angle, while traveling through a curved portion of the target Travel route, calculates a target value that reaches a maximum steering angle at a circular arc curve portion that continuously follows a transition curve portion of the curved section; a target deceleration calculation unit that calculates a target deceleration in the curved section, which causes a maximum Lateral acceleration in the circular arc portion is equal to or smaller than a set value; a deceleration correction value calculating unit that calculates a corrected vehicle speed for correcting a target vehicle speed determined by the target deceleration on the basis of the target steering angle and an actual steering angle calculated speed; anda deceleration correction unit that corrects the target deceleration so that the vehicle speed becomes the corrected vehicle speed, the deceleration correction value calculating unit calculating, as the corrected vehicle speed, a vehicle speed at the actual steering angle that causes the value of a curvature of one traveled by the vehicle Curve becomes equal to a turning curve at the target steering angle and the target vehicle speed.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese Patent Application No. 2015-068383 , filed March 30, 2015, the entire contents of which are hereby incorporated by reference.

BACKGROUND

Technical area

The present invention relates to a travel support system for a vehicle which causes the vehicle to follow a target travel route through steering control and deceleration control.

Related technology

In a vehicle such as an automobile, steering control and brake control are generally provided as independent functions. For example, when the vehicle is turning during deceleration, there arises a problem that a steering operation amount or a braking operation amount to be applied by the driver increases, thereby increasing an operating burden on the driver.

The Japanese Unexamined Patent Application Document JP 2011 - 162 004 A discloses a technique of selecting whether the steering control or the braking control is mainly performed in order to solve this problem; a main page request value that is a requested value of a vehicle turning motion to be performed is output to a main page based on the voting result; and a non-main page request value, which is a requested value corresponding to a difference between a target value and the main page request value, is output to a non-main page to thereby ensure cooperative control of the steering control and brake control and the operator burden of the Reduce driver.

the JP 2009 - 292 345 A discloses a travel assistance system for a vehicle having a target steering angle calculating unit and a target deceleration calculating unit that enables the deceleration to be corrected to take into account a driver's feeling when approaching a curve.

the DE 39 12 353 A1 discloses a self-steering vehicle and method of operating the same, and US Pat DE 10 2006 017 406 A1 discloses a method of operating a steering system.

SUMMARY OF THE INVENTION

However, the one in the JP 2011-162 004 A disclosed technique only with the unambiguous assignment of the requested value of the vehicle turning movement to the steering control and deceleration control, and it cannot be said that the cooperation timing and the degree of cooperation of the two controllers are necessarily optimized.

For example, when the vehicle is traveling along a curvy target travel route as shown in FIG 6th In the steering control, due to the feedback correction component which compensates for the response delay and the control error, the control trajectory as shown in the figure with a broken line is actually realized, the behavior of the vehicle suspension system is disturbed and the ride quality may deteriorate become. Even if the assignment of the deceleration control is increased and the feedback correction component of the steering control is clearly decreased in order to avoid such a result, the steering reversal may occur and the accuracy with which the vehicle follows the target travel route may decrease.

The present invention has been made in view of the foregoing, and it is an object of the present invention to provide a travel support system for a vehicle which can optimize cooperative control of steering control and deceleration control and suppresses malfunction of the vehicle suspension system while the target - Route follow-up accuracy is ensured.

This object is achieved by a drive support system for a vehicle according to claim 1. Advantageous embodiments of the invention are defined in the subclaims

One aspect of the present invention provides a travel support system for a vehicle which causes the vehicle to follow a target travel route through steering control and deceleration control, the travel support system comprising: a target steering angle calculating unit which is calculated while traveling through a curved portion of the vehicle Target travel route calculates a target steering angle as a target value, so that a maximum steering angle is obtained at a circular arc curve portion that continuously follows a transition curve portion of the curved section; a target deceleration calculating unit that calculates a target deceleration in the curved portion as a deceleration at which a maximum lateral acceleration in the circular arc curve portion becomes equal to or less than a set value; a deceleration correction value calculating unit that calculates, on the basis of the target steering angle and an actual steering angle, a corrected vehicle speed obtained by correcting the target vehicle speed determined by the target deceleration; and a deceleration correction unit that corrects the target deceleration so that the target vehicle speed becomes the corrected vehicle speed.

Figure list

• 1 Fig. 13 is a configuration diagram of a travel support system for a vehicle;
• 2 Fig. 13 is an explanatory drawing showing the target travel route when entering a curve;
• 3 Fig. 13 is an explanatory drawing showing the target steering angle and the target deceleration when entering a corner;
• 4th Fig. 13 is an explanatory drawing showing the correction of the target vehicle speed;
• 5 Fig. 3 is a flow chart of cornering control; and
• 6th Fig. 13 is an explanatory drawing showing the conventional control trajectory during cornering.

DETAILED DESCRIPTION

Embodiments of the present invention will be described below with reference to the drawings. In 1 denotes the reference number 1 a driving support system for a vehicle that performs driving support control including automatic driving based on outside environment recognition results for the vehicle related to driving operations of a driver. The driving assistance system 1 is on a trip control device 10 turned off and is by connecting an outdoor environment monitor 20th , an engine control device 30th , a brake control device 40 , a steering control device 50 , a warning control device 60 and the like with an on-board network 100 configured.

The outdoor environment monitor 20th is configured by a combination of a group of devices that can autonomously recognize the outside environment and a group of devices that acquire information by communicating with the outside. The first group of devices includes a camera unit 20A that recognizes the outside environment by processing captured images of the environment around the vehicle, and a radar unit (laser radar, millimeter wave radar, ultrasonic radar and the like) 20B that receives waves reflected from three-dimensional objects around the vehicle. The latter group of devices includes a vehicle position measuring unit 20C which measures the position (latitude, longitude, altitude) of the vehicle by means of a global positioning system (GPS) or the like, a navigation unit 20D that integrates with the vehicle position measuring unit 20C is configured to perform route guidance by displaying the measured position of the vehicle on a map image, and, using accurate map data stored in the system, position coordinate data on the shape and junctions (intersections) of the road, road type data ( Highway, expressway, urban road, etc.), and outputs data related to information of facilities or buildings located in the vicinity of nodes on the map, and a road traffic information communication unit 20E that acquires road traffic information through road-to-vehicle communication or vehicle-to-vehicle communication.

In the present embodiment, the camera unit is 20A by integrating a stereo camera 21 and an image processing unit 22nd configured. The stereo camera 21 is for example from a couple constructed by left and right cameras using solid-state image pickup elements such as CCD and CMOS. The two cameras are attached at a predetermined distance from one another, for example on the front of the interior ceiling of the vehicle cabin, record the stereo image of an object outside the vehicle from different points of view and transmit the recorded image to the image processing unit 22nd the end.

The image processing unit 22nd generates distance information based on the triangulation measurement principle from the amount of offset of the respective positions with respect to the pair of left and right images in front of the vehicle by the two left and right stereo cameras 21 have been recorded. The outside environment such as spatial objects, white lines on the road, and guard rails in front of the vehicle are recognized based on the distance information, and the vehicle travel route is calculated based on the recognized information. The image processing unit 22nd also detects a vehicle ahead on the vehicle route based on data on the detected spatial object, calculates the distance between the vehicle and the vehicle ahead, the speed (relative speed) of the vehicle ahead relative to the vehicle and the acceleration (deceleration) of the vehicle ahead and outputs the calculation results to the travel control device as preceding vehicle information 10 the end.

The engine control device 30th is a per se known control device that controls the operating state of the engine (not shown in the figure) of the vehicle, for example, main controls such as fuel injection control, ignition timing and opening degree control of an electronically controlled throttle valve on the basis of the air intake amount, the throttle opening degree, the engine water temperature , intake air temperature, air-fuel ratio, crank angle, accelerator operation amount, and other types of vehicle information.

The brake control device 40 is for example a well-known anti-lock braking system, the braking devices of four wheels (not shown in the figure) on the basis of a brake switch, the speed of the four wheels, the steering wheel angle, the yaw rate and other types of vehicle information independent of that of the driver brake operation performed, or a per se known control device that performs yaw brake control or yaw moment control for controlling the yaw moment applied to the vehicle, such as anti-skid control. When a braking force of the wheels from the travel control device 10 is input, the brake controller calculates 40 the brake hydraulic pressure for each wheel based on the braking force and operates a brake drive unit (not shown in the figure).

The steering control device 50 is, for example, a per se known control device which generates an assist torque generated by an electric power steering motor (not shown in the figure) provided in the steering system of the vehicle on the basis of the vehicle speed, the steering torque generated by the driver, the Controls steering wheel angle, yaw rate, and other types of vehicle information. The steering control device 50 is also capable of lane departure prevention control for performing lane keeping control to keep the aforementioned lane as a set lane, as well as control that prevents the vehicle from deviating from the lane. The steering angle or the steering torque required for such lane keeping control and lane departure avoidance control are determined by the travel control means 10 calculated and in the steering control device 50 is input and the driving of the electric power steering motor is controlled according to the inputted control amount.

The warning control device 60 generates a warning as necessary when an abnormality occurs in various devices of the vehicle. For example, a warning or message is output by means of a visual output, for example with a monitor, a display or an alarm lamp, and / or an audio output with a loudspeaker or buzzer. Further, when the driving support control is stopped by the driver performing an override operation, the driver is informed of the current operating condition.

The trip control device 10 , which is the main component of the driving assistance system 1 with the above-described devices, the driving support control including automatic driving by cooperation of driving control including follow-up driving, lane keeping control and lane departure avoidance control performs based on the information from the devices 20th , 30th , 40 and 50 and the operating status information of the vehicle obtained from a plurality of sensors 70 such as a vehicle speed sensor, a steering angle sensor, a Yaw rate sensor and a lateral acceleration sensor are detected by. In particular, during cornering in automatic driving, the cooperative control of the steering control and the deceleration control is carried out in an optimized manner to suppress changes in the vehicle body behavior while maintaining the target route following accuracy.

The cruise control device is used for this purpose 10 , as in 1 shown, provided with a target route calculation unit 11 , a target steering angle calculation unit 12th , a target delay calculation unit 13th , a delay correction value calculation unit 14th , a delay correction unit 15th and a steering angle control unit 16 , as cooperative control functions for steering and decelerating when cornering. The cooperative steering and deceleration control with these functional units optimizes the yaw control by the brakes and suppresses control oscillations due to a response delay or an error in the yaw control caused by steering. With such control, by optimally setting the delay time and amount of delay in entering the corner, the amount of feedback correction of the steering control is reduced without causing the steering to reverse, thereby suppressing the disturbance of the vehicle suspension system while maintaining the target Route follow-up accuracy is maintained.

In particular, the target travel route calculation unit calculates 11 the target travel route of the vehicle based on the position information (latitude, longitude) of the vehicle obtained from the external environment monitor 20th has been acquired, positions (latitude, longitude) of the nodes on the map data representing the route, linear segments of the road, data on the curved segment (transition curve portion, circular arc curve portion) and data on white lines on the road. The target travel route of the vehicle when cornering is, for example, as shown in 2 shown, set as a way in which the linear section S with the circular arc curve portion C2 with a constant curve radius R through the transition curve portion C1 is associated with a curve depth (crossing angle) θ. In a vehicle coordinate system in which the position of the center of gravity of the vehicle is taken as the origin point and the front of the vehicle is taken as the X-axis and the lateral direction of the vehicle is taken as the Y-axis, the target travel route is calculated as a curve that passes through the center of the lane of the vehicle, which is recognized from the road shape data and white line data.

The target steering angle calculation unit 12th calculates a target steering angle δref for traveling along the target travel route based on, for example, the speed V of the vehicle, the vehicle position (x, y), and the yaw angle θyaw with respect to the target travel route, and outputs the calculated target steering angle to the delay correction value calculating unit 14th and the steering angle control unit 16 the end. The target steering angle δref in the curved section contains a target steering angle δref_cl in the transition curve portion and a target steering angle δref_r in the circular arc portion and is, as in FIG 3 is calculated as a target value such that a steering angle waveform in the transition curve portion C1 converges to a maximum steering angle δmax that is derived from the curve radius (minimum radius) R in the circular arc curve portion C2 and the vehicle specifications.

Here, the target steering angle is δref_cl in the transition curve portion C1 calculated as the setpoint at which the lateral acceleration (lateral jerk: d ³ y / dx ³ ) of the vehicle is minimal. For example, a function J (x) obtained by taking a derivative of a polynomial with respect to the jerk minimization curve as indicated by the following expression (1) and determining the target steering angle as a waveform is applied that minimizes the value of the function J (x). In the expression (1), A and B are setting parameters related to the waveform. $$\text{J}\left(\text{x}\right)=\mathrm{30th}\cdot {\left(\text{x / A}\right)}^{\mathrm{4th}}-60\cdot {\left(\text{x / A}\right)}^3+\mathrm{30th}\cdot {\left(\text{x / A}\right)}^2\cdot {\text{B / A}}^2$$

The target deceleration calculation unit calculates on the basis of the target travel route (X, Y, R) 13th , as a target deceleration Dref, that deceleration at which the maximum transverse acceleration at the curve radius (minimum radius) R is equal to or less than a set value (e.g. 0.2G). As in 3 shown, the setpoint deceleration Dref is a deceleration that enables the vehicle in the region of the transition curve portion C1 to decelerate to the target vehicle speed, and in the circular arc curve portion C2 to drive at constant speed.

The delay correction value calculation unit 14th calculates a correction value for correcting the target deceleration Dref based on that from the target steering angle calculation unit 12th calculated target steering angle δref and an actual steering angle δH detected by a steering angle sensor. the Correction value is a vehicle speed correction value for increasing or decreasing the target deceleration Dref according to the difference between the target steering angle δref and the actual steering angle δH, and is calculated as the corrected vehicle speed (target vehicle speed after correction) Vref2 at which Actual steering angle δH the same angle of rotation or the same cornering curvature as the turning angle or cornering curvature is obtained at the target steering angle δref and the target vehicle speed Vref. Then the target deceleration Dref is set by the deceleration correction unit 15th is corrected so that the target vehicle speed Vref determined by the current target deceleration Dref becomes the corrected vehicle speed Vref2.

By setting the deceleration with the optimal timing and increasing or decreasing the yaw moment generated by the brakes in response to the deviation from the target travel route, the feedback component of the steering angle control based on the difference between the target travel route is thus Steering angle δref and the actual steering angle δH based, reduced without generating a reverse rotation of the steering. As a result, control swing can be prevented and the malfunction of the vehicle suspension system can be suppressed while the target travel route following accuracy is ensured.

In particular, for example, as in 4th , the relationship between the steering angle δ, the rotation (of the vehicle, that is, the curvature of a curve on which the vehicle is traveling) ρ and the vehicle speed V are mapped in advance, and the generated correction map is referred to on the basis of the target steering angle δref and of the current actual steering angle δH. 4th represents the case in which the actual steering angle δH is smaller than the target steering angle δref. In this case, the vehicle speed at the actual steering angle δH at which a rotation equal to the turning angle or the cornering curvature at the target steering angle δref of the target vehicle speed Vref is obtained as a corrected vehicle speed Vref2 at the low-speed Page is determined, and the target deceleration Dref is increased so that the current target vehicle speed Vref becomes the corrected vehicle speed Vref2 which is a low speed.

On the other hand, if the actual steering angle δH has exceeded the target steering angle δref and has become too large due to a road edge or the like, the corrected vehicle speed Vref2 is determined to be a vehicle speed that is higher than the target vehicle speed Vref, and the target vehicle speed is Deceleration Dref is reduced so that the current target vehicle speed Vref becomes the corrected vehicle speed Vref2, which is high speed. If the actual steering angle δH thus deviates from the target steering angle δref, the target deceleration δref is increased or decreased accordingly and the deviation of the target steering angle δH from the target steering angle δref is compensated.

wobei $$\text{Ast}=-\text{M}\cdot \left(\text{Lf}\cdot \text{Kr}-\text{Lr}\cdot \text{Kr}\right)/\left(2\cdot \text{Kf}\cdot \text{Kr}\cdot \text{L}\right);$$

Kf:

Seitenführungskraft des Vorderrads;

Kr:

Seitenführungskraft des Hinterrads;

Lf:

Abstand zwischen Schwerpunkt und Vorderrad;

Lr:

Abstand zwischen Schwerpunkt und Hinterrad

L:

Radstand (Lf + Lr); und

M:

Fahrzeugmasse.

The correction map for determining the corrected vehicle speed Vref2 can be generated by the two-wheel constant-radius cornering model used when the turning or cornering curvature in the transition curve portion changes linearly for each constant position, or by matching the the current vehicle is used. The following expression (2) represents the relationship between the steering angle δ and the rotation p obtained with the two-wheel model. The corrected vehicle speed Vref2 resulting from constant rotation can be determined with the correction map generated from these relationships. $$\mathrm{\delta }=\left(\text{1 / R}\right)-(\text{L.}-\text{M.}\cdot {\text{V}}^2\cdot \left(\text{Lf}\cdot \text{Kr}-\text{Lr}\cdot \text{Kr}\right)/\left(2\cdot \text{Kf}\cdot \text{L.}\right)=\mathrm{\rho }\cdot \left(\text{L.}+\text{branch}\cdot {\text{V}}^2\right)$$

in which $$\text{branch}=-\text{M.}\cdot \left(\text{Lf}\cdot \text{Kr}-\text{Lr}\cdot \text{Kr}\right)/\left(2\cdot \text{Kf}\cdot \text{Kr}\cdot \text{L.}\right);$$

Kf:

Cornering force of the front wheel;

Kr:

Cornering force of the rear wheel;

Lf:

Distance between center of gravity and front wheel;

Lr:

Distance between the center of gravity and the rear wheel

L:

Wheelbase (Lf + Lr); and

M:

Vehicle mass.

The delay correction unit 15th corrects the target deceleration Dref such that the target vehicle speed Vref becomes the corrected target vehicle speed Vref2 after a preset time Td. When the preset time Td is long, the effect of the deceleration correction becomes weak, and when the preset time Td is short, the deceleration feeling or the pitch change feeling given to the driver is intensified and the driving feeling is deteriorated. Therefore, the preset time is optimally set by matching that the actual vehicle uses.

wobei:

Kv:

Motor-Spannung-Strom-Umwandlungsfaktor;

Kp:

Proportional-Verstärkung;

Ki:

Integral-Verstärkung;

Kd:

Differenzial-Verstärkung; und

Kf:

vorwärts koppelnde Verstärkung im Bezug auf Kurvenfahrt.

The steering angle control unit 16 calculates the target steering torque based on the difference between the target steering angle δref and the actual steering angle δH, and controls the electric power steering motor through the steering controller 50 on. This control of the target torque is used in particular as current control of the electric power steering motor by the steering control device 50 carried out. For example, the electric power steering motor is driven by a drive current IM represented by the following expression (3) based on PID control. $$\text{I.}=\text{Kv}\cdot \left(\text{Kp}\cdot \left(\mathrm{\delta }\text{ref}-\mathrm{\delta }\text{H}\right)+\text{Ki}\cdot {\displaystyle \int \left(\mathrm{\delta }\text{ref}-\mathrm{\delta }\text{H}\right)\text{German}+\text{Kd}\cdot \text{d}\left(\mathrm{\delta }\text{ref}-\mathrm{\delta }\text{J}\right)/\text{German}+\text{Kf / R}}\right)$$

in which:

Kv:

Motor voltage-current conversion factor;

Kp:

Proportional gain;

Ki:

Integral gain;

Kd:

Differential gain; and

Kf:

forward coupling reinforcement in relation to cornering.

In this case, the feedback correction component in the steering angle control is essentially reduced by setting the yaw braking by correcting the target deceleration Dref, which is implemented in parallel with the steering angle control. As a result, the vehicle can be made to follow the target travel route accurately while suppressing the malfunction of the vehicle suspension system by the changes in the feedback correction.

The cornering control program process carried out by the travel control device 10 is carried out, is carried out using the in 5 illustrated flowchart.

In the cornering control, the initial step S1 the shape data on the curve in front of the vehicle (depth of curve, curve minimum radius, clothoid parameters, road width, white line shape, etc.) from the forward recognition information from the camera unit 20A and map information from the navigation unit 20D is acquired, and the target route of the vehicle is calculated on the basis of this data.

The process then goes to step S2 further where the target steering angle δref is calculated in the curve section. The target steering angle δref is a target value that provides a waveform so that the lateral jerk in the transition curve portion is minimized and a maximum steering angle δmax determined by the curve radius R and vehicle specifications is obtained in the circular arc curve portion (see FIG 3 ).

Then in step S3 calculates the target deceleration Dref at which the vehicle is decelerated to the target vehicle speed Vref. The target delay Dref is a target value like this. that the transverse acceleration in the circular arc curve portion that continuously follows the transition curve portion of the curved section is equal to or less than a predetermined constant value (for example, 0.2 G).

The process then goes to step S4 further, and it is checked whether the vehicle position has entered the transition curve portion of the curved portion or not. If the vehicle position has not yet entered the curve (transition curve portion), the routine is stopped, and if the vehicle position has entered the curve (transition curve portion), the process goes to Schritt S5 further.

In step S5 the actual steering angle δH detected by the steering angle sensor is read and in step S6 the corrected vehicle speed Vref2 resulting from constant rotation with respect to the target vehicle speed Vref, for example, using the correction map (see FIG 4th ) is calculated based on the target steering angle δref and the actual steering angle δH. Then in step S7 corrects the target deceleration Dref by increasing or decreasing the current target deceleration Dref by a set amount to obtain the corrected vehicle speed Vref2 after the lapse of the set time Td. As a result of the correction of the target deceleration Dref, the feedback correction component, which is determined by the difference between the target steering angle δref and the actual steering angle δH in the transition curve portion, is reduced.

Then the process goes to S8 further, and it is determined whether or not a deceleration end portion connected to the circular arc curve portion having the minimum radius of curvature of the transition curve portion has been passed. As a result, when the deceleration end section has been passed, the process goes on S9 further, the deceleration control of cornering is canceled and the output of the control signal (target brake hydraulic pressure) to the brake drive unit by the brake control device 40 canceled. If the end of delay section has not been passed, the process goes to step S10 Further, the deceleration control of cornering is continued and the output of the control signal (target brake hydraulic pressure) to the brake operation unit is continued.

By setting the optimal delay timing and the delay in entering a corner, the present embodiment makes it possible to reduce the feedback correction component of the steering control without causing the steering to reverse and to suppress the disturbance of the vehicle suspension system. while the target route follow-up accuracy is ensured.

A travel support system for a vehicle that causes the vehicle to follow a target travel route through steering control and deceleration control includes: a target steering angle calculation unit that calculates a target steering angle while traveling through a curved portion of the target travel route; a target deceleration calculating unit that calculates a target deceleration in the curved portion; a deceleration correction value calculating unit that calculates a corrected vehicle speed for correcting a target vehicle speed determined by the target deceleration based on the target steering angle and an actual steering angle; and a deceleration correction unit that corrects the target deceleration so that the vehicle speed becomes the corrected vehicle speed.

Claims (3)

Driving support system for a vehicle which, by means of steering control and deceleration control, causes the vehicle to follow a target driving route, the driving support system having: a target steering angle calculating unit which, as a target steering angle while traveling through a curved section of the target travel route, calculates a target value which reaches a maximum steering angle at a circular arc curve portion that continuously follows a transition curve portion of the curved portion; a target deceleration calculating unit that calculates a target deceleration in the curved portion that causes a maximum lateral acceleration in the circular arc curve portion to be equal to or smaller than a set value; a deceleration correction value calculating unit that calculates a corrected vehicle speed for correcting a target vehicle speed determined by the target deceleration based on the target steering angle and an actual steering angle; and a deceleration correction unit that corrects the target deceleration so that the vehicle speed becomes the corrected vehicle speed, the deceleration correction value calculating unit calculating, as the corrected vehicle speed, a vehicle speed at the actual steering angle that causes the value of a curvature of one traveled by the vehicle Curve becomes equal to a turning curve at the target steering angle and the target vehicle speed. Driving assistance system for a vehicle according to Claim 1 ; wherein the steering angle calculating unit calculates, as the target steering angle, a target value at which lateral acceleration is minimized in the transition curve portion, the target value in the circular arc curve portion reaches the maximum steering angle, and the maximum steering angle is obtained based on a minimum curve radius and vehicle specifications . Driving assistance system for a vehicle according to one of the Claims 1 or 2 wherein the deceleration correction unit corrects the target deceleration such that the target vehicle speed becomes the corrected vehicle speed after a set time.

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